20" X 20" Sound Rated Steel Access Panel Felt Covered Door For Concealed Wall / Ceiling Application With Slotted Lock - [Outer Dimensions: 21" Width X 21" Height] 6" Diameter + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 28" x 6" OR 6" x 28" duct opening (measured at the opening)

+ Product Details Size – 18" x 34" or 34" x 18" is the size for the duct opening measurement only

actual front end outer dimensions are approximately 27 5/8" width X 24 5/8" height

+ Product Details Perfect Fit & Easy Sizing - Designed for a 26" x 28" OR 28" x 26" duct opening (measured at the opening)

Design – Fixed hinged for easy filter change & cleaning - uses a 1" thick filter

20" X 20" Sound Rated Steel Access Panel Felt Covered Door For Concealed Wall / Ceiling Application With Slotted Lock - [Outer Dimensions: 21" Width X 21" Height] 6" Diameter + Product Details Perfect Fit+ Product Details Size 20" X 20" is the size for the drywall opening measurement only, actual front end outer dimensions are 21" Width X 21" Height High Quality High grade steel construction. Design 1mm galvanized steel material with sleek, shiny, durable white powder coat finish for an attractive look & high durability corrosion protection 15mm medium density fibreboard with felt cover and rubber sealing between the door and frame for tight security.